Generally, arrangements for protecting shafts from exposure to debris or damage have been previously discussed in the art. Representative of such prior proposals is U.S. Pat. No. 4,568,313, issued Feb. 4, 1986, to Diffenderfer et al. The reference details a bellow type cover suited for articulated shafting. The device is a simple dust cover for use in limited environments.
Chaczyk, in U.S. Pat. No. 4,988,113, issued Jan. 29, 1991, provides a sealed protective boot. The boot surrounds a reciprocating shaft for preventing debris from contacting the shaft. Although a useful system, the boot is prone to premature wear, since the boot must absorb the continuous compression and expansion forces. The wear created from this problem is accelerated upon the accretion of debris, fluids etc. on the boot.
In U.S. Pat. No. 5,407,570, issued to Hobson, Jr., Apr. 18, 1995, a flexible filter element is disclosed. The device includes a spring extended between the ends of the arrangement, with one end sealed by a screw. The concept of the invention is to facilitate reuse of the filter as damage occurs in the form of tears, holes etc., in the filter material. As this occurs, the filter is simply shortened by removing the damaged area and screwing the end back onto the arrangement. As is evident, the spring is thus progressively compressed and thus inherently increases the tension of the filter material and thus the proclivity for expedited wear.
Other prior art marginally relevant to the invention includes U.S. Pat. Nos. 4,439,219 and 4,702,483.
In view of the advances made in the prior art, there exists a need for a sleeve or in-line type filter capable of long term heavy duty. The present invention addresses this need.